Sofa



FIG. 1 is a plan view of a sofa showing our new design;

FIG. 2 is a front view thereof;

FIG. 3 is a right side view, the left side view being the same;

FIG. 4 is a rear view thereof; and

FIG. 5 is a bottom view. 

The ornamental design for a sofa, as shown and described. 